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HOPCAT, 6dF & Star Formation Rates
Marianne T. DoylePh.D. Project
ContentThe HIPASS - 6dFGS Connection
My Project
Investigate the question: How does star
formation depend upon environment
and other factors?
Finding optical counterparts for the HIPASS
catalogue
Investigating the Morphology-density
relation using Star Formation Rates, Star
Formation Efficiency and Galaxy Density
Supervisor:Michael J. Drinkwater – UQAssoc. Supervisors:Elaine Sadler – Uni SydneyJohn Ross - UQCollaborators David J. Rohde - UQMike Read – WFAU
EdinburghBaerbel Koribalski – ATNF,
EppingHIPASS Team – ATNF Parkes
& Epping, Universities of : Melbourne, Cardiff, Western Sydney Macarthur, Wales, Swinburne, Technology Sydney, New Mexico, Manchester, Colorado, Sydney, LeicesterASTRON The Netherlands,AAO Sydney,WIYN Tucson etc….......
The 6dFGS - HIPASS Connection HI Parkes Sky Survey (HIPASS)
HI blind radio survey of the southern sky up to Dec=2o
October 2001: 2710 “additional” targets were added to the 6dfGS (Thank you Michael Drinkwater)
Optical objects included are: within 5 arcmin of the HIPASS positions R mag < 17“NOT” already in one of the official optical target lists for 6dF
341 - highest priority: multiple matches to radio position 1558 - main sample 811 - faint sample (16.7<R<17)
My PhD Project
The question: How does the conversion of hydrogen to stars (star formation) depend upon environment and other factors?
Testing two theories: Either fewer “star forming galaxies” actually
form in regions of high galaxy density,
OR There are physical processes that directly
suppresses star formation.
Steps Use radio detected galaxy sample instead of optical
sample Optical samples are biased towards star forming
galaxies which is what we are trying to measure.
Star Formation Rate (SFR)
Star Formation Efficiency (SFE)
Local galaxy density
YrMSFR Solar /Hz W 2.3
Lum1-22
1.4GHz
1
YrMass
SFRSFE
HI
2
10
11DegGal
Area RadiusGalaxythGalaxy
Optical Counterpart - HOPCAT
HIPASS Catalogue (HICAT) contains 4315 HI radio sources
Find optical counterparts Accurate galaxy position needed to measure
luminosity to calculate SFR
Search for “Dark Galaxies”
Optical Data
OPTICAL IMAGES SuperCOSMOS 15’ x 15’ Images
7’ radius Radio-Optical position uncertainty
IMAGE ANALYSIS SExtractor Image Analysis.
Radio-Optical Position Uncertainty
Is that the right galaxy? Many images have multiple galaxies Crosscheck HIPASS velocity with optical or high
resolution radio velocities Published velocities – NED
Information from catalogues, surveys & the literatureData varies in quality
Need a high quality dataset6dF velocities (Kindly supplied by Heath)
Developed an automated visual interactive program
ADRIC
Unobserved areas
Results Optically Matched with velocity 58% 2516
Single Match (44% - 1882) Compact group member (14% - 634)
Optically Matched with no velocity 26% 1107 Single Match (20% - 851) Compact group member (6% - 256)
No Guess 11% 476
Several galaxies no velocities
Blank Field 5% 216 No visible galaxy
Any Isolated Dark Galaxies in HIPASS? 4315 HI detected objects Extinction cut at ABj < 1 - 3692 objects Use only blank fields - 13 objects Take out over crowded fields - 2 object remaining 2 remaining objects?
1 is a very faint previously observed galaxy in the Centaurus group
1 ruled out with Narrow-band follow-up observations at Parkes as a non-detection
Conclusion: No isolated dark galaxies are present in the HIPASS survey
HOPCAT’s Galaxy density coverage Galaxies in
regions with Low galaxy density? Large sample
Galaxies in regions with High galaxy density? Very small
sample
Solution?ATCA high resolution HI observations to find/confirm optical counterpart in regions of high galaxy density
Star Formation & Density SUMSS radio continuum data
304 Sumss – HOPCAT matches
Galaxy Density 10th Galaxy radius Galaxy number / degree2
Star Formation Rate Star Formation Efficiency
Star Formation Rate Vs Density
Ave density=0.07
SFR ave=1.3
Ave density =0.9
Ave SFR = 0.34
Ave density = 12
Ave SFR = 0.5
Ave density = 86
Ave SFR = 1.2
SUMSS – Sydney University Molonglo Sky Survey 304 Sumss –
HOPCAT matches
Galaxy Density 10th Galaxy radius Galaxy number /
degree2
Star Formation Efficiency Vs Density
Summary
2710 optical galaxies near HIPASS positions were added to the 6dFGS list
Superimposed ellipses
Yellow for correct match
15 x 15 arcmin images to allow
for the 7 arcmin position uncertaintyCentred on
HICAT positions
Selection parameters
Original
HICAT parameters
Superimposed and listedPublished velocities
ADRIC
interactive visual matching program